This demo was developed a few years ago using Unity 4. This is basically a simple mini game of picking up the floating/spinning squares with the ball. Roll it to victory. This demo was built using C# language. The tutorials are available on Unity 3D’s site.
The demo may not run on some browsers (like Chrome and Microsoft Edge). It does work on Firefox, Internet Explore, and Opera. The demo requires Unity Web Player to be installed for it to launch on the browser. It will prompt to install Unity Web Player if not already installed.
So of course this is the problem, just like Flash player, this created application using Unity 3D was done before HTML5 became mainstream. I apologize for the inconvenience if you choose to install the Unity Web Player. If you do get to try this demo, please leave some feedback in the comments.